1. Field of the Invention
The present invention relates to a maintenance apparatus of a recording head in an image recording apparatus which records an image in a recording medium.
2. Description of the Related Art
In general, as a printer, there is known one which has recording heads based on an inkjet scheme and discharges ink droplets to a paper sheet carried by paper feeding means from a plurality of nozzles of these recording heads, thereby recording an image having a high quality at a high speed.
Meanwhile, in such a printer, it is often the case that foreign particles such as paper particles of a recording paper sheet adhere to an ink discharge opening of an ink chamber constituting an inkjet recording head to provoke clogging or air bubbles enter the ink discharge opening to collapse surface tension of the ink, and discharge of the ink from the ink chamber becomes impossible or a discharge direction is deflected by these factors.
Therefore, it has been conventionally determined that a maintenance operation for rapidly recovering from such a situation is necessary. As this maintenance method, there is a method by which an entire nozzle plate on which nozzles are arranged is covered and all the nozzles are simultaneously sucked or some of the nozzles are sucked, thereby removing foreign particles or the ink which has adhered to the nozzles.
For example, as shown in FIG. 40, Jpn. Pat. Appln. No. H5-201028 discloses a maintenance apparatus for a recording head, which brings a sucking portion 154 having a suction opening 155 sucked by negative pressure generating means 153 consisting of a pump or the like to touch a surface on which nozzles 152 of a head main body 151 while moving the sucking portion 154 by suction opening moving means 156, thereby sucking and removing foreign particles or an ink which has adhered to all the nozzles 152
Further, in Japanese Patent No. 3161050discloses a maintenance apparatus of a recording head, which has a configuration in which a suction opening is brought to touch an ink jet recording head, and a suction pump is driven to suck an ink inside/outside nozzles and foreign particles or the like on a head main body end surface, thereby effecting maintenance processing. At this time, an air current becomes parallel with the head main body end surface around the suction opening so that ink droplets, an outflow of ink, foreign particles and others which have adhered to the head main body end surface are drawn and sucked into the suction opening. Furthermore, Japanese Patent No. 3065818 discloses a maintenance apparatus which moves a sucking portion of an ink suction unit along a surface of an orifice, cleans and collects ink droplets or foreign particles which have adhered to a surrounding part of the orifice, thus removing a factor of a discharge defect.
In the configuration disclosed in Jpn. Pat. Appln. No. H5-201028, an ink or the like is pulled out in a perpendicular direction which is the same as an ink squirting direction of nozzles by a suction force of a suction opening which is to touch a nozzle surface. Therefore, the ink breaks into small pieces in the vicinity of a nozzle end portion, and hence there is a problem that bubbles are apt to be generated. That is, when suction is performed from the suction opening in the perpendicular direction of the nozzle openings (i.e., the ink squirting direction), the ink in the nozzles broke off into small pieces. As a result, the ink or foreign particles in the nozzles can be sucked and removed, but air bubbles remain in the nozzles after execution of the maintenance, which can be a factor which avoids discharge of the ink or deflects an ink discharge path.
In the maintenance apparatus disclosed in Japanese Patent No. 3161050 mentioned above, when performing suction in the maintenance processing, an air stream (or air current) generated by a vacuum nozzle flows in a direction which cuts longitudinally a nozzle string (a direction along a direction of the nozzle string). In such suction, since the air stream passes and flows above many nozzles in such a manner that it cuts longitudinally the nozzle string, foreign particles such as dust or an ink remaining on an nozzle surface (dust included in this ink) which is moved by the air stream travels above other nozzles or passes through a nozzle surface along a long direction. When the air stream passes therethrough, the nozzles may be newly clogged, the nozzle surface may be damaged, whereby a meniscus cannot be formed in some cases.
Moreover, in suction based on such a flow direction of an air stream, it is difficult to suck an ink or foreign particles remaining on surfaces along both sides of the nozzle string into the vacuum nozzle. For example, when an end portion of the suction opening is scanned for suction while being to touch the nozzle surface so that a negative pressure entirely acts on the nozzles, clogging of the nozzles can be eliminated. However, scanning movement of the suction opening causes an air stream to flow along a scanning direction and pass to cut longitudinally an upper side of the plurality of nozzles, which is the same as the above-described structure.
In Japanese patent No. 3065818, some of the nozzles are covered with and sucked by the sucking portion and the sucking portion is moved to suck all the nozzles, but a detailed shape of the sucking portion which covers the nozzles, especially a positional relationship between an orifice surface and the sucking portion is not clearly disclosed. When the sucking portion is appressed against a head surface to perform suction, a negative pressure entirely acts on the nozzles, and hence the inside of the nozzles can be sucked to eliminate clogging, but there is no guarantee that foreign particles or contamination which has adhered to a peripheral part of the nozzles can be removed, which may possibly result in the same inconvenience as that in Japanese Patent No. 316050.